N2 -Naphthalenesulfonyl-L-arginine derivatives, and the pharmaceutically acceptable acid addition salts thereof

ABSTRACT

N 2  -naphthalenesulfonyl-L-arginine amides having the formula ##STR1## or the acid addition salts thereof with a pharmaceutically acceptable acid wherein R 1  is alkenyl of not more than 10 carbon atoms, or substituted alkyl containing not more than 20 carbon atoms wherein said substituent is a member selected from the class consisting of alkoxy, alkoxycarbonyl, arylcarbamoyl acyl, acyloxy, N,N-polymethylenecarbamoyl and carboxy, and R 2  is aryl, cycloalkyl, aralkyl or cycloalkylalkyl, respectively containing not more than 15 carbon atoms and R&#39; is 1-naphthyl substituted with a member selected from the class consisting of 2-dialkylamino, 3-dialkylamino, 4-dialkylamino, 6-dialkylamino, 7-dialkylamino, 8-dialkylamino, respectively containing not more than 20 carbon atoms, and 5-dialkylamino containing 3-20 carbon atoms; or 2-naphthyl substituted with dialkylamino containing not more than 20 carbon atoms.

CROSS-REFERENCE TO RELATED APPLICATIONS

This is a division of application Ser. No. 760,740, filed Jan. 19, 1977,now U.S. Pat. No. 4,069,329, which in turn is a continuation-in-part ofapplication Ser. No. 671,435, filed on Mar. 29, 1976, now U.S. Pat. No.4,062,963 which in turn is a continuation-in-part application of Ser.No. 622,390, filed Oct. 14, 1975, now abandoned.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to certain new and useful N²-naphthalenesulfonyl-L-arginine esters and amides, and thepharmaceutically acceptable acid addition salts thereof, which are ofespecial value in view of their outstanding antithrombotic properties.

2. Description of the Prior Art

In the past, there have been many attempts to obtain new and improvedagents for the treatment of thrombosis. Of these, N²-(p-tolylsulfonyl)-L-arginine esters are known to be effective indissolving blood clots. (U.S. Pat. No. 3,622,615, patented Nov. 23,1971). Also, N² -dansyl-L-arginine esters and amides are disclosed inU.S. Pat. application No. 496,939, now U.S. Pat. No. 3,978,045. A needcontinues to exist, however, for a highly specific inhibitor on thrombinfor the control of thrombosis.

SUMMARY OF THE INVENTION

Accordingly, one object of the present invention is to provide a classof N² -naphthalenesulfonyl-L-arginine esters, amides andpharmaceutically acceptable acid addition salts thereof.

Another object of the present invention is to provide a class of N²-naphthalenesulfonyl-L-arginine esters, amides and pharmaceuticallyacceptable acid addition salts thereof which are useful in thediagnostic selective determination of thrombin in blood and in drugtherapy as antithrombotic agents.

Briefly, these objects and other objects of the present invention ashereinafter will become more readily apparent can be attained by N²-naphthalenesulfonyl-L-arginine esters and amides of formula (I):##STR2## or the acid addition salts thereof with a pharmaceuticallyacceptable acid, wherein R is selected from the class consisting of (1)alkoxy, alkenyloxy, halogenated alkoxy, alkynyloxy and cycloalkoxy,respectively containing not more than 10 carbon atoms, aralkyloxy of notmore than 15 carbon atoms or not more than 10 carbon atoms,tetrahydrofurfuryloxy, and alkoxy of not more than 10 carbon atomssubstituted with an alkoxy group of not more than 10 carbon atoms;halogen or nitro; ##STR3## wherein R₁ and R₂ are members selected fromthe class consisting of hydrogen, alkyl, aryl, alkenyl and cycloalkyl,respectively containing not more than 10 carbon atoms, and aralkyl andcycloalkylalkyl, respectively containing not more than 15 carbon atoms,and substituted alkyl containing not more than 20 carbon atoms, saidsubstituent being selected from the class consisting of alkoxy,alkoxycarbonyl, acyl, acyloxy, arylcarbamoyl andN,N-polymethylenecarbamoyl, respectively containing not more than 10carbon atoms, and carboxy; and ##STR4## wherein Z is a divalent groupcontaining up to 10 or 20 carboxyl carbon atoms, which consists of morethan one group selected from the class consisting of methylene --CH₂ --,monosubstituted methylene ##STR5## wherein R₃ is selected from the classconsisting of alkyl, acyl, alkoxy, and alkoxycarbonyl, respectivelycontaining not more than 10 carbon atoms, and carbamoyl, anddisubstituted methylene ##STR6## wherein R₄ and R₅ are alkyl groups ofnot more than 10 carbon atoms, and which may further contain at leastone member selected from the class consisting of oxy--O--, thio--S--,cycloalkylene of not more than 10 carbon atoms, imino ##STR7##alkyl-substituted imino ##STR8## wherein R₆ is an alkyl group of notmore than 10 carbon atoms, acyl-substituted imino ##STR9## wherein R₇ isan alkyl group of not more than 10 carbon atoms, carbonyl and phenylene##STR10## which may be arranged in any order and complete the ##STR11##ring together with the said methylene, monosubstituted methylene ordisubstituted methylene; and R' is a member selected from the classconsisting of 1-naphthyl substituted with 2-, 3-, 4-, 6-, 7-, or 8-dialkylamino, respectively containing not more than 20 carbon atoms,5-dialkylamino containing 3-20 carbon atoms, 2-naphthyl substituted withdialkylamino containing not more than 20 carbon atoms.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Now the inventon is explained in detail with respect to specific aspectsthereof.

In the above formula (1), examples of R are as follows:

(1) In the case of ester derivatives, examples of R are an alkoxy groupcontaining not more than 10 carbon atoms, e.g., methoxy, ethoxy,isopropoxy, propoxy, butoxy, tertbutoxy, pentyloxy, hexyloxy and thelike; a cycloalkoxy group containing not more than 10 carbon atoms,e.g., cyclohexyloxy and the like; a halogenated alkoxy group containingnot more than 10 carbon atoms, e.g., 2-chloroethoxy, 4-chlorobutoxy andthe like; an alkoxy group of not more than 10 carbon atoms substitutedwith an alkoxy group of not more than 10 carbon atoms, e.g.,2-methoxyethoxy, 2-ethoxyethoxy and the like; an alkenyloxy groupcontaining not more than 10 carbon atoms, e.g., allyloxy, 2-butenyloxyand the like; or an aralkyloxy group containing not more than 15 carbonatoms, e.g., benzyloxy, phenethyloxy, 1-phenylethoxy, 1-phenylpropoxyand the like.

(2) In the case where ##STR12## examples of R₁ and R₂ are independentlya hydrogen atom, an alkyl group containing not more than 10 carbonatoms, e.g., methyl, ethyl, propyl, isopropyl, butyl, isobutyl, pentyl,hexyl, heptyl and the like; an aryl group containing not more than 10carbon atoms, e.g., phenyl, tolyl and the like; an aralkyl groupcontaining not more than 15 carbon atoms, e.g., benzyl, phenethyl,3-phenylpropyl and the like; a cycloalkyl group containing not more than10 carbon atoms, e.g., cyclopropyl, cyclohexyl and the like; acycloalkylalkyl group containing not more than 15 carbon atoms, e.g.,cyclohexylmethyl, 3-cyclohexylpropyl and the like; an alkenyl groupcontaining not more than 10 carbon atoms, e.g., allyl, crotyl, 2-hexenyland the like; and an alkyl group containing not more than 10 carbonatoms substituted with an alkoxy group, an alkoxycarbonyl group, an acylgroup, an acyloxy group, an arylcarbamoyl group or anN,N-polymethylenecarbamoyl group, respectively containing not more than10 carbon atoms or a carboxy group, e.g., methoxyethyl, methoxypropyl,ethoxyethyl, ethoxycarbonylmethyl, 2-ethoxycarbonylethyl,2-methoxycarbonylethyl, 3-ethoxycarbonylpropyl, 2-acetylethyl,2-acetoxyethyl, 2-phenylcarbamoylethyl,N,N-tetramethylenecarbamoylmethyl and the like.

(3) In the case where ##STR13## examples of R are a 1-polymethyleniminylgroup, and those contaning oxo or thio group, respectively containingnot more than 10 carbon atoms, and a 1-polymethyleniminyl groupcontaining not more than 10 carbon atoms substituted with an alkyl,acyl, alkoxy, or alkoxycarbonyl group, respectively containing not morethan 10 carbon atoms, or carbamoyl, e.g., azetidinyl,3-methoxy-1-azetidinyl, 3-ethoxy-1-azetidinyl, 1-pyrrolidinyl,2-ethoxycarbonyl-1-pyrrolidinyl, 2-pyrrolidon-1-yl, piperidino,4-piperidon-1-yl, 4-methylpiperidino, 4-ethylpiperidino,4-propylipiperidino, 4-isopropylpiperidino, 2-methylpiperidino,3-methylpiperidino, 2-ethoxycarbonyl-1-pyrrolidinyl,4-methoxypiperidino, 4-oxopiperidino, 4-acetylpiperidino,4-methoxycarbonylpiperidino, 4-carbamoylpiperidino,1-hexamethyleniminyl, 1-octamethyleniminyl and the like; an oxazole andthiazole, such as 3-oxazolidinyl, 3-thiazolidinyl, and the like; anisoxazole and isothiazole, such as 2-isoxazolidinyl, 2-isothiazolidinyl,and the like; an oxazine, such as morpholino, 2,6-dimethylmorpholino,and an oxazine group represented by tetrahydro-1,n-oxazin-n-yl, such astetrahydro-1,3-oxazin-4-yl and the like; a thiazine, such astetrahydro-1,4-thiazin-4-yl and the like; 4-methyl-1-piperazinyl,4-acetyl-1-piperazinyl, 1-piperazinyl, 2-isoindolinyl, 1-indolinyl,1,2,3,4-tetrahydro-2-isoquinolyl, 4-azabicyclo-[3.2.2]-non-4-yl,1,2,3,4-tetrahydro-1-quinolyl and the like.

Examples of R' are 1- or 2-naphthyl substituted with dialkylamino of notmore than 20 carbon atoms, e.g., dimethylamino, diethylamino and thelike (excepting 5-dimethylamino-1-naphthyl). Included are compoundswherein R' is 1-naphthyl substituted with 5-dialkylamino containing 3-10carbon atoms, and 2-naphthyl substituted with a member selected from theclass consisting of dialkylamino containing not more than 10 carbonatoms.

In the formula (I), R is preferably alkoxy of 1-8 carbon atoms,aralkyloxy of 7-9 carbon atoms, alkenyloxy of 3-6 carbon atoms,cyclohexyloxy, ω-alkoxyalkoxy of 2-6 carbon atoms, ω-chloroalkoxy of 2-6carbon atoms, alkylamino of 1-9 carbon atoms, ω-alkoxy alkylamino of 2-6carbon atoms, ω-alkoxycarbonylalkylamino of 2-8 carbon atoms,alkenylamino of 3-5 carbon atoms, cycloalkylamino of 3-6 carbon atoms,cyclohexylmethylamino, arylamino of 6-10 carbon atoms, aralkylamino of7-10 carbon atoms, dialkylamino of 2-10 carbon atoms,N-alkyl-N-(ω-alkoxycarbonylalkyl)amino of 4-8 carbon atoms,N-alkyl-N-(ω-alkoxyalkyl)amino of 3-8 carbon atoms,N-alkyl-N-aralkylamino of 8-10 carbon atoms,N-alkyl-N-(ω-acylalkyl)amino of 4-8 carbon atoms, N,N-polymethyleniminylof 3-10 carbon atoms, N,N-polymethyleniminyl of 3-10 carbon atomssubstituted with alkyl of 1-5 carbon atoms, alkoxy of 1-5 carbon atoms,alkoxycarbonyl of 2-5 carbon atoms, acyl of 2-5 carbon atoms, orcarbamoyl; tetrahydro-1,n-oxazin-n-yl, tetrahydro-1,n-thiazin-n-yl,wherein n is an integer of 2, 3 or 4, tetrahydro-1,n-oxazin-n-yl,wherein n is an integer of 2, 3 or 4 and which is substituted with oneor two alkyl groups of 1-5 carbon atoms; 2-isoindolinyl, 1-piperazinyl,1-piperazinyl substituted with alkyl of 1-5 carbon atoms or acyl of 2-5carbon atoms, 4-alkyl-1-piperazinyl of 5-8 carbon atoms, or4-azabicyclo[3.2.2]-non-4-yl.

R' is preferably 6-(N,N-dimethylamino)-2-naphthyl, or5-(N,N-diethylamino)-1-naphthyl.

Typical compounds of this invention include N²-(5,6,7,8-tetrahydro-1-naphthalenesulfonyl)-N-benzyl-L-argininamide;4-ethyl-1-[N²-(5-diethylamino-1-naphthalenesulfonyl)-L-arginyl]piperidine; and4-ethyl-1-N² -(6-dimethylamino-2-naphthalenesulfonyl)-L-arginyl)piperidine.

These typical compounds are highly potent in their antithromboticactivity.

For the preparation of the compounds of this invention, various methodscan be employed depending upon the particular starting materials and/orintermediates involved. Successful preparation of these compounds ispossible by way of several synthetic routes which are outlined below.

(1) Preparation of N² -naphthalenesulfonyl-L-arginine esters.

(a) Esterification of an N² -naphthalenesulfonyl-L-arginine.

N² -naphthalenesulfonyl-L-arginines, which are the starting materialsfor the preparation of N² -naphthalenesulfonyl-L-arginine esters, aremost generally obtained by reacting L-arginine and a naphthalenesulfonylhalide, in the presence of a base.

The naphthalenesulfonyl halides to be used are represented by thegeneral formula R'-SO₂ X, wherein R' is the same as in formula (I) and Xis a halogen atom such as chlorine or bromine. Usually anaphthalenesulfonyl chloride is preferred.

However, N² -naphthalenesulfonyl-L-arginines may also be obtained byreacting ornithine, the ω-position of which is protected, with anaphthalenesulfonyl halide in the presence of a base, removing theprotective group at the ω-position of the product, and thereafterguanidylating the N² -naphthalenesulfonylornithine by conventionalprocedures.

N² -naphthalenesulfonyl-L-arginine esters or acid addition salts thereofare prepared by esterifying the above-mentioned N²-naphthalenesulfonyl-L-arginine in accordance with the processesexplained below.

(i) Esterification by heating an N² -naphthalenesulfonyl-L-arginine andan alcohol.

The reaction rate is low in this method, which is therefore conductedunder high pressure at an elevated temperature. Care must be exercised,since N² -naphthalenesulfonyl-L-arginines are easily decomposed at hightemperatures.

(ii) Esterification of an N² -naphthalenesulfonyl-L-arginine with analcohol in the presence of an esterification catalyst.

Suitable esterification catalysts include hydrogen halides, such ashydrogen chloride, hydrogen bromide or the like; mineral acids such assulfuric acid, nitric acid, phosphoric acid, or the like; organic acids,such as toluenesulfonic acid, benzenesulfonic acid, methanesulfonicacid, trifluoromethanesulfonic acid, trifluoroacetic acid, cationic ionexchange resins or the like; and Lewis acids, such as borontrifluoroide, aluminum chloride, or the like. Strong acids areespecially suitable.

A strong acid esterification catalyst adds to an N²-naphthalenesulfonyl-L-arginine ester to form an acid addition saltthereof. In the case of an N²-dialkylaminonaphthalenesulfonyl-L-arginine ester, 2 equivalents or moreof the acid is preferably used, since 2 equivalents of the acid addsthereto.

Suitable alcohols for the above-mentioned esterification includeprimary, secondary, and tertiary alkyl alcohols containing up to 10carbon atoms, such as methanol, ethanol, propanol, isopropyl alcohol,butanol, tert butyl alcohol, pentanol, hexanol, 2-ethylhexanol; aralkylalcohols containing up to 15 carbon atoms, such as benzyl alcohol,phenethyl alcohol, 1-phenylethanol, 1-phenyl-1-propanol, or the like;alkenyl alcohols containing up to 10 carbon atoms, such as allylalcohol, crotyl alcohol, methyl vinyl carbinol, or the like; cycloalkylalcohols containing up to 10 carbon atoms, such as cyclohexanol,cyclopentanol, or the like; and alkyl alcohols containing up to 10carbon atoms substituted with an alkoxy group of up to 10 carbon atomsor a halogen, such as 3-chloro-1-propanol, 2-chloro-1-propanol,1-chloro-2-propanol, 2-fluoro-1-ethanol, 2-chloro-1-ethanol,4-chloro-1-butanol, 2-methoxyethanol, 3-ethoxypropanol, or the like.

An N² -naphthalenesulfonyl-L-arginine reacts with an equimolar amount ofan alcohol. However, at least 5 moles of the alcohol per mole of the N²-naphthalenesulfonyl-L-arginine are preferably employed to enhance thereaction rate.

The esterification reaction can be carried out in a reaction-inertsolvent, such as an aromatic hydrocarbon, e.g., benzene, toluene,xylene, or the like; a chlorinated hydrocarbon, e.g., carbontetrachloride, chloroform, dichloromethane, or the like; a hydrocarbonsolvent, e.g., hexane, cyclohexane, or the like; an ether, e.g.,dioxane, tetrahydrofuran, or the like; or a mixture of these compounds.Especially preferred solvents include benzene, toluene, xylene,cyclohexane, carbon tetrachloride and dichloromethane, which formazeotropic mixtures with water, and are therefore advantageous for theesterification reaction, since water formed during the reaction can beeasily removed, and the reaction can be carried out advantageously atequilibrium.

The reaction temperature varies with the alcohol and the catalyst to beemployed. Generally, the temperature ranges from 0° C. to the boilingpoint of the alcohol or solvent. The reaction time varies widely withthe alcohol and catalyst employed and normally ranges from 10 minutes to15 hours.

After the reaction is completed, the alcohol and/or solvent is distilledoff, and N² -naphthalenesulfonyl-L-arginine ester or an acid additionsalt thereof is obtained. However, as hereinbefore mentioned, in thecase of the N² -dialkylaminonaphthalenesulfonyl-L-arginine ester, 2equivalents of acid adds thereto. The acid addition salt can be easilyconverted to the corresponding N² -naphthalenesulfonyl-L-arginine esterby adjusting the pH of the medium.

The N² -naphthalenesulfonyl-L-arginine esters and the acid additionsalts thereof can be purified by recrystallization from a combination ofsolvents, such as ethyl ether, alcohols, acetone or the like, orreprecipitating by addition of ether to an alcohol solution of thecompounds.

(iii) Esterification of an N² -naphthalenesulfonyl-L-arginine with analcohol and a thionyl halide.

Suitable thionyl halides include thionyl chloride and thionyl bromide.The N² -naphthalenesulfonyl-L-arginine reacts with an equimolar amountof the thionyl halide. However, it is desirable to employ at least 2moles of the thionyl halide per one mole of the N²-naphthalenesulfonyl-L-arginine in order to drive the reaction tocompletion. During the reaction, the thionyl halide decomposes to ahydrogen halide and SO₂, and the formed hydrogen halide adds to the N²-naphthalenesulfonyl-L-arginine ester to generally form a halogen acidsalt of the N² -naphthalenesulfonyl-L-arginine ester.

The other reaction conditions and the procedures for separation andpurification of the product are the same as in process (ii)(esterification with an esterification catalyst).

(iv) Preparation of an N² -naphthalenesulfonyl-L-arginine methyl ester.

An N² -naphthalenesulfonyl-L-arginine methyl ester can be prepared bythe reaction of an N² -naphthalenesulfonyl-L-arginine with diazomethane;reaction of an N² -naphthalenesulfonyl-L-arginine with dimethyl sulfiteand tosylsulfonic acid; and reaction of an N²-naphthalenesulfonyl-L-arginine with dimethyl sulfate.

(v) Reaction of an alkali metal salt of an N²-naphthalenesulfonyl-L-arginine with an alkyl halide.

Alkyl esters of an N² -naphthalenesulfonyl-L-arginine can be prepared byreacting an alkali metal salt of an N² -naphthalenesulfonyl-L-arginineand an alkyl halide in a polar solvent.

In addition, an N² -naphthalenesulfonyl-L-arginine may be esterified byother processes, but processes (ii) and (iii) are generally used.

(b) Reaction of an L-arginine ester with a naphthalenesulfonyl halide.

L-arginine esters or acid addition salts thereof, which are used as thestarting materials of N² -naphthalenesulfonyl-L-arginine esters or acidaddition salts thereof, are most generally obtained by reactingL-arginine with an alcohol in the presence of an acid catalyst. When theesterification is carried out in the presence of an acid catalyst, anacid addition salt of an L-arginine ester is usually obtained.

The naphthalenesulfonyl halides usable for this process has been definedhereinbefore.

The reaction of an L-arginine ester or an acid addition salt thereofwith a naphthalenesulfonyl halide is normally carried out in thepresence of a base. The base captures the hydrogen halide formed duringthe reaction and enhances the reaction rate.

Suitable bases include organic bases, such as triethylamine, pyridine,or the like; and common inorganic bases such as sodium hydroxide,potassium hydroxide, potassium carbonate, or the like. The inorganicbases are usually used as an aqueous solution.

The base is normally used in an amount at least equivalent to theL-arginine ester. When an acid addition salt of an L-arginine ester isused as the starting material, an excess of the base sufficient toconvert the L-arginine ester acid addition salt to the L-arginine esteris desirably used in addition to the amount to be used as the catalyst.

The naphthalenesulfonyl halide reacts with an equimolar amount of anL-arginine ester of an acid addition salt thereof. The reaction of anL-arginine ester or an acid addition salt thereof and anaphthalenesulfonyl halide is usually carried out in a solvent. Suitablesolvents include water; chlorinated solvents, such as dichloromethane,chloroform, carbon tetrachloride, and the like; aromatic hydrocarbons,such as benzene, toluene, xylene and the like; ethers such as ethylether, tetrahydrofuran, tetrahydropyran and the like; ketones such asacetone, methyl ethyl ketone, cyclohexanone and the like; basicsolvents, such as dimethylacetamide, dimethylformamide, tetramethylurea,N-methyl-pyrrolidone, pyridine, quinoline, and the like; or a mixture oftwo or more of these solvents. A basic solvent acts as an acid acceptor,and therefore the addition of the base is unnecessary when such solventis used.

The reaction temperature is dependent on the arginine esters and basesto be employed, but is generally between 0° C. and the boilingtemperature of the solvent employed.

The reaction time varies with the arginine ester and is usually between10 minutes and 15 hours.

After the reaction is completed, the produced salt is washed away withwater, the solvent is removed by distillation, and the obtained productis washed with water and/or the solvent. To the thus obtained N²-naphthalenesulfonyl-L-arginine ester, an acid (e.g., hydrochloric acid,p-toluenesulfonic acid, or the like) is added, and the formed acidaddition salt of the N² -naphthalenesulfonyl-L-arginine ester isisolated.

(2) Preparation of N² -naphthalenesulfonyl-L-argininamides.

(a) Reaction of an N² -naphthalenesulfonyl-L-arginine ester with aprimary amine.

Suitable N² -naphthalenesulfonyl-L-arginine esters or the acid additionsalts thereof include the methyl ester, ethyl ester, isopropyl ester andthe like or the hydrochlorides thereof. Suitable amines include primaryamines, such as an alkylamine containing not more than 10 carbon atoms,e.g., methylamine, ethylamine, propylamine, isopropylamine, butylamine,hexylamine, heptylamine and the like; an aralkylamine containing notmore than 15 carbon atoms, e.g., phenethylamine and the like; acycloalkylamine containing not more than 10 carbon atoms, e.g.,cyclopropylamine, cyclobutylamine, cyclopentylamine, cyclohexylamine,cyclooctylamine, 4-methylcyclohexylamine, and the like; and alkylaminecontaining not more than 10 carbon atoms substituted with an alkoxygroup containing not more than 10 carbon atoms, e.g.,2-methoxyethylamine, 2-ethoxyethylamine, 3-methoxypropylamine,3-methoxybutylamine, 3-methoxypentylamine and the like; acycloalkylalkylamine containing not more than 15 carbon atoms, e.g.,cyclohexylmethylamine, 2-cyclohexylethylamine, cyclobutylmethylamine,3-cyclopentylbutylamine and the like, and an alkenylamine containing notmore than 10 carbon atoms, e.g., allylamine, crotylamine, 3-butenylamineand the like.

The amine is preferably used in an amount equivalent to or greater thanthe N² -naphthalenesulfonyl-L-arginine ester. The amine is preferablyused in excess in order to enhance the reaction rate and to carry outthe reaction advantageously at equilibrium. The amine is usually used inan amount 2 to 10 times the molar quantity of the N²-naphthalenesulfonyl-L-arginine ester. When an acid addition salt of anN² -naphthalenesulfonyl-L-arginine ester is used, the amine is usuallyconverted to an acid addition salt. Therefore, it is necessary to use anamine corresponding to the acid addition salt of the amine to be formedin excess.

A basic compound may be used as a catalyst. Specifically, an alkalimetal alkoxide, such as sodium methoxide or a tertiary amine, such aspyridine or the like are preferable. When these catalysts are used, thereaction rate is enhanced and therefore the amine can be used in alesser amount and milder reaction conditions are thus possible.

If the amine is used in large excess, N² -naphthalenesulfonyl-L-arginineesters or acid addition salts thereof will dissolve in the amine, andtherefore the reaction will proceed without a solvent. However,solvents, such as alcohols, e.g., methanol, ethanol, butanol and thelike; ethers, e.g., ethyl ether, tetrahydrofuran, tetrahydropyran,dioxane and the like; hydrocarbons, e.g., benzene, toluene, cyclohexaneand the like; halogenated hydrocarbons, e.g., carbon tetrachloride,chloroform, dichloromethane and the like; and water can be used.

The reaction is usually carried out by mixing an N²-naphthalenesulfonyl-L-arginine ester or an acid addition salt thereofwith an excess amount of an amine, the resulting homogeneous solution isallowed to stand at room temperature. However, the reaction mixture canbe heated to a temperature up to the boiling temperature of the amine orsolvent to enhance the reaction rate.

The reaction time is dependent on the basicity and amount of the amineemployed, among other factors, but usually ranges from several hours toseveral days.

After the reaction is completed, the product is collected by filtration,washed with water, and purified by recrystallization from a suitablesolvent, e.g., aqueous methanol, or the like. If solid product does notform, the excess amine and/or the solvent is removed by distillation,and the residue is washed and purified by recrystallization from asuitable solvent.

(b) Reaction of an L-argininamide with a naphthalenesulfonyl halide.

An L-argininamide or an acid addition salt thereof can be obtained byprotecting the guanidino group and α-amino group of the arginine vianitration, acetylation, formylation, phthaloylation,trifluoroacetylation, p-methoxybenzyloxycarbonylation, benzoylation,benzyloxycarbonylation, t-butoxycarbonylation or tritylation, thencondensing the obtained arginine derivative with an amine by aconventional method such as the acid halide method, azide method, mixedanhydride method, activated ester method, carbodiimide method, or thelike, and thereafter removing the protective group by the known method.The suitable naphthalenesulfonyl halides have already been explainedhereinbefore with respect to the preparation of N²-naphthalenesulfonyl-L-arginines.

The reaction of an L-argininamide or an acid addition salt thereof and anaphthalenesulfonyl halide is usually carried out in the presence of abase. The basic compound captures the hydrogen halide which is formedduring the reaction, and thus promotes the reaction.

Suitable bases include organic bases such as triethylamine, pyridine andthe like; or inorganic bases, such as sodium hydroxide, potassiumhydroxide, potassium carbonate and the like. Inorganic bases are usuallyused as an aqueous solution.

The base is used in excess of the amount equivalent to theL-argininamide. When an acid addition salt of an L-argininamide is used,a base is preferably used in an amount sufficient to convert the acidaddition salt of the L-argininamide to the free L-argininamide inaddition to the amount of the base to be used as the catalyst.

A naphthalenesulfonyl halide is usually reacted with an equimolar amountof an L-argininamide or an acid addition salt thereof in a solvent.Suitable solvents include water; chlorinated hydrocarbons such asdichloromethane, chloroform, carbon tetrachloride and the like; aromatichydrocarbons, such as benzene, toluene, xylene and the like; ethers,such as ethyl ether, tetrahydrofuran, dioxane, tetrahydropyran and thelike; ketones, such as acetone, methyl ethyl ketone, cyclohexanone andthe like; basic solvents, such as dimethylacetamide, dimethylformamide,tetramethylurea, N-methylpurrolidone, pyridine, quinoline and the like;or a mixture of two or more of these solvents. A basic solvent acts asan acid acceptor, and therefore further addition of the base is notrequired in these instances.

The reaction temperature is dependent on the species of theL-argininamide and base, but usually between 0° C. and the boilingtemperature of the solvent. The reaction time varies with theL-argininamide and is usually between 10 minutes and 15 hours.

After the reaction is completed, the formed salt is removed by washingwith water, solvent is removed by distillation, and the obtained productis washed with water and/or the solvent, and the N²-naphthalenesulfonyl-L-argininamide is obtained. The thus obtained N²-naphthalenesulfonyl-L-argininamide can be isolated in the form of anacid addition salt thereof by the addition of an acid (e.g.,hydrochloric acid, p-toluenesulfonic acid, and the like).

(c) Elimination of the N^(G) -substituent from an N^(G) -substituted-N²-naphthalenesulfonyl-L-argininamide having the formula (II). ##STR14##An N² -naphthalenesulfonyl-L-argininamide is prepared by eliminating theN^(G) -substituent from an N^(G) -substituted-N²-naphthalenesulfonyl-L-argininamide having the above formula (II) bymeans of acidolysis or hydrogenolysis. In the formula (II), R and R' arethe same as in the formula (I), X and Y are selected from hydrogen andprotective groups for the guanidino group, and at least one of them is aprotective group. Suitable protective groups include nitro, tosyl,trityl, or an oxycarbonyl, such as benzyloxycarbonyl,p-altrobenzyloxycarbonyl, p-methoxybenzyloxycarbonyl, tertbutoxycarbonyland the like.

The N^(G) -substituted-N² -naphthalenesulfonyl-L-argininamides asrepresented by general formula (II) or acid addition salts thereof canbe obtained by condensing an N^(G) -substituted N² -substituted arginine(usually the N² -substituent is a protective group for the amino group,such as benzyloxycarbonyl, t-butoxycarbonyl, or the like) and an aminevia the azide method, mixed anhydride method, activated ester method,carbodiimido method or the like, selectively removing only the N²-substituent by means of catalytic hydrogenolysis or acidolysis, andreacting the thus obtained N^(G) -substituted-L-argininamide or an acidaddition salt thereof with a naphthalenesulfonyl halide, as defined inthe above, in the presence of a base in a solvent. Suitable basesinclude organic bases, such as triethylamine, pyridine and the like; orinorganic bases, such as sodium hydroxide, potassium hydroxide,potassium carbonate, sodium hydrogen carbonate and the like. Inorganicbases are normally used as an aqueous solution.

The base is preferably used in an amount not less than the amountequivalent to the N^(G) -substituted-L-argininamide. When an acidaddition salt of an N^(G) -substituted-L-argininamide is used, the baseis preferably used in an amount sufficient to neutralize the acidaddition salt in addition to the amount to be used as the catalyst. Thenaphthalenesulfonyl halide is normally used in an equimolar amount tothe N^(G) -substituted-L-argininamide.

Suitable solvents include water; chlorinated solvents, such asdichloromethane, chloroform, carbon tetrachloride and the like; aromatichydrocarbons, such as benzene, toluene, xylene and the like; ethers,such as ethyl ether, tetrahydrofuran, dioxane and the like; ketones,such as acetone, methyl ethyl ketone, cyclohexanone, and the like; basicsolvents such as dimethylacetamide, dimethylformamide, tetramethylurea,N-methylpyrrolidone, pyridine, quinoline, and the like; or a mixture oftwo or more of the above-mentioned solvents. A basic solvent acts as anacid acceptor, and therefore further addition of the base is notrequired in these instances.

The reaction temperature is dependent on the N^(G)-substituted-L-argininamide and base, but usually ranges from -10° C. tothe boiling temperature of the solvent.

The reaction time varies with the species of the X^(G)-substituted-L-argininamide and base, and the reaction temperature, andis usually from 5 minutes to 24 hours.

After the reaction is completed, the solvent and base are distilled off,the formed salt is removed by washing with water, and the N^(G)-substituted-N² -naphthalenesulfonyl-L-argininamide is purified byrecrystallizing or reprecipitating from a suitable solvent. The reactionproduct may also be separated and purified by means of chromatography.Suitable elutants include chlorinated solvents, such as chloroform,dichloromethane and the like; a chlorinated solvent containing alcoholand the like.

As explained above, the N² -naphthalenesulfonyl-L-argininamiderepresented by general formula (II) or an acid addition salt thereof isobtained from the N^(G) -substituted-N² -naphthalenesulfonyl-L-argininamide by removing the N^(G) -substituent, which is aprotective group for the guanidino group of the amide, viahydrogenolysis or acidolysis.

Suitable acids for the acidolysis include hydrogen halides, such ashydrogen chloride, hydrogen bromide, hydrogen fluoride; and organicacids, such as trifluoroacetic acid, trifluoromethanesulfonic acid,formic acid, acetic acid, and the like.

The acidolysis is preferably carried out by treating the N^(G)-substituted-N² -naphthalenesulfonyl-L-argininamide or the acid additionsalt thereof with any of the above-mentioned acids without a solvent orin a solvent, such as an alcohol, e.g., methanol, ethanol and the like;an ether, e.g., tetrahydrofuran, dioxane, anisole and the like; anorganic acid. e.g., acetic acid and the like; or an ester, e.g., ethylacetate and the like, at a temperature between -10° C. and +100° C.,preferably at room temperature. The time required for the acidolysisvaries with the acid and solvent, the protective N^(G) substituent, andthe temperature of treatment, and is from 30 minutes to 24 hours.

After the decomposition is completed, the N²-naphthalenesulfonyl-L-argininamide or an acid addition salt thereof isobtained by removing the solvent and the excess acid or adding to thereaction mixture an inert solvent, such as ethyl ether, petroleum ether,a hydrocarbon solvent, or the like so as to form a precipitate andcollecting the precipitate. An excess of the acid is usually used, andtherefore the N² -naphthalenesulfonyl-L-argininamide which is obtainedby removing the protective group is in the form of an acid additionsalt. This salt can be easily converted to a free amide byneutralization.

Hydrogenolysis can be carried out according to any of the generalprocedures of reductive hydrogenation although catalytic hydrogenationis most advantageous. Catalytic hydrogenation is carried out in thepresence of a hydrogen-activating catalyst in a hydrogen atmosphere.Suitable hydrogen-activating catalyst include Raney nickel, palladium,platinum and the like. Suitable solvents include alcohols, such asmethanol, ethanol and the like; ethers, such as dioxane, tetrahydrofuranand the like; organic acids, such as acetic acid, propionic acid and thelike; or a mixture of two or more of the above-mentioned solvents.

The reaction temperature is dependent on the protective group for theguanidino group and the activity of the employed catalyst, and isusually between 0° C. and the boiling temperature of the solvent. Thehydrogen pressure is dependent on the reaction temperature and activityof the catalyst. Atmospheric pressure is sufficient for the reaction,although higher pressure may be employed. The reaction time is dependenton the activity of the catalyst, the reaction temperature, the hydrogenpressure and the like and is usually from 2 hours to 120 hours.

After the hydrogenolysis is finished, the catalyst is removed byfiltration, the solvent is removed by distillation, and the N²-naphthalenesulfonyl-L-argininamide or the acid addition salt thereof isobtained. The acid addition salt is easily converted to the free N²-naphthalenesulfonyl-L-argininamide by neutralization.

The thus obtained N² -naphthalenesulfonyl-L-argininamide or the acidaddition salt thereof is purified by recrystallization from a solventwhich is a mixture of two or more of the following: water, ethyl ether,alcohols, acetone, or the like, or by reprecipitation by addition ofethyl ether to an alcohol solution of the compound.

(d) Reaction of an N² -naphthalenesulfonyl-L-arginyl halide and anamine.

An N² -naphthalenesulfonyl-L-argininamide is prepared by reaction of acorresponding N² -naphthalenesulfonyl-L-arginyl halide and an amine. TheN² -naphthalenesulfonyl-L-arginyl halide is prepared by reacting acorresponding N² -naphthalenesulfonyl-L-arginine with a halogenatingagent such as thionyl chloride, phosphorus oxychloride, phosphorustrichloride, phosphorus pentachloride, phosphorus tribromide. etc.

Although the halogenation proceeds without solvent, an inert solventsuch as chlorinated hydrocarbons, e.g., chloroform, dichloromethane,etc., ethers, e.g., tetrahydrofuran, dioxane, etc., may preferably beused.

Usually the halogenating agent is used at least in an equimolar amountto the N² -naphthalenesulfonyl-L-arginine.

The amount of the solvent to be used is not critical. But it is suitableto use a solvent in an amount 5-100 times the weight of the N²-naphthalenesulfonyl-L-arginine.

The preferred reaction temperature is in the range of from -10° C. toroom temperature. The reaction time varies with the halogenating agentand reaction temperature, and usually is from 15 minutes to 5 hours.

Amidation proceeds without solvent, but the use of a solvent such asdimethylformamide, and halogenated solvent (chloroform, dichloromethane,etc.), gives better results. Usually the amine is used at least in anequimolar amount to the N² -naphthalenesulfonyl-L-arginyl halide.

The amount of the solvent to be used is not critical, but is usuallyabout 5-100 times by weight the amount of the N²-naphthalenesulfonyl-L-arginyl halide.

The preferred reaction temperature is in the range of from -10° C. toroom temperature. The reaction time depends on the species of the amineand usually is from 3 minutes to 10 hours.

(e) Guanidylation of an N² -naphthalenesulfonyl-L-ornithinamide or anacid addition salt thereof.

An N² -naphththalenesulfonyl-L-argininamide or an acid addition saltthereof is prepared by guanidylating a corresponding N²-naphthalenesulfonyl-L-ornithinamide or an acid addition salt thereof.The guanidylation is performed by using ordinary guanidylating agentssuch as an O-alkylisourea an S-alkylisothiourea,1-guanyl-3,5-dimethylpyrazole, carbodimide, etc., and O-alkylisourea andS-alkylisothiourea are especially preferred guanidylating agents.

The reaction of the N² -naphthalenesulfonyl-L-ornithinamide or its acidaddition salt with an O-alkylisourea or an S-alkylisothiourea is carriedout usually in the presence of a base. The bases to be used includeorganic bases such as triethylamine, pyridine, etc.; common inorganicbases such as sodium hydroxide, potassium hydroxide, potassiumcarbonate, etc. Inorganic bases are usually used in the form of anaqueous solution.

The base is used in an amount of 0.01 to 0.1 equivalent to the N²-naphthalenesulfonyl-L-ornithinamide. When an acid addition salt of anN² -naphthalenesulfonyl-L-ornithinamide is used as the startingmaterial, it is necessary to use a base in an amount sufficient toneutralize the acid addition salt.

The O-alkylisourea or S-alkylisothiourea is usually used in theequimolar amount.

Generally, the reaction of an N² -naphthalenesulfonyl-L-ornithinamide oran acid addition salt thereof with an O-alkylisourea or anS-alkylisothiourea is conducted in a solvent.

The preferred solvents include: water; alcohols such as methanol,ethanol, propanol, etc.; ethers such as tetrahydrofuran, dioxane,tetrahydropyran, etc.; ketones such as acetone, methyl ethylketone,etc.; basic solvents such as dimethylacetamide, dimethylformamide, etc.;and mixtures of any two or more of them.

The reaction temperature varies with the N²-naphthalenesulfonyl-L-ornithinamide and base, and usually is between 0°C. and the boiling temperature of the solvent.

The reaction time varies with the N²-naphthalenesulfonyl-L-ornithinamide, base, solvent and the employedreaction temperature, and usually is in the range of from 30 minutes. to50 hours.

After the reaction is completed, the solvent is distilled off and theexcess base and the formed salt are removed by washing with water.

The N-² -naphthalenesulfonyl-L-argininamide is obtained by purifying theproduct by column chromatography with silica gel.

The thus obtained N² -naphthalenesulfonyl-L-argininamide may be treatedwith ether and an acid such as hydrochloric acid, p-toluenesulfonicacid, etc. to isolate the acid addition salt of the N²-naphthalenesulfonyl-L-argininamide. N² -naphthalenesulfony-L-arginineesters and amides of this invention having the formula (I) form acidaddition salts with any of a variety of inorganic and organic acids. Theproduct of the reactions described above can be isolated as the freebase or as the acid addition salt. In addition, the product can beobtained as pharmaceutically acceptable acid addition salts by reactingone of the three bases with an acid, such as hydrochloric, hydrobromic,hydroiodic, nitric, sulfuric, phosphoric, acetic, citric, maleic,succinic, lactic, tartaric, gluconic, benzoic, methanesulfonic,ethanesulfonic, benzenesulfonic, p-toluenesulfonic acid or the like.

As stated above, N² -naphthalenesulfonyl-L-arginine esters and amides,and acid addition salts thereof of this invention are characterized byhighly specific inhibitory activity in mammals against thrombin, andtherefore these compounds are useful in the determination of thrombin inblood as diagnostic reagents, and/or for the medical control orprevention of thrombosis.

The antithrombotic activities of the N² -naphthalenesulfonyl-L-argininederivatives of this invention were compared with those of a knownantithrombotic agent. [N² -(p-tolylsulfonyl)-L-arginine methyl ester],by determining the fibrinogen coagulation time. The measurement of thefibrinogen coagulation time was conducted as follows:

An 0.8 ml aliquot of a fibrinogen solution, which had been prepared bydissolving 150 mg of bovine fibrinogen (Cohn fraction I) supplied byArmour Inc. in 40 ml of a borate saline buffer (pH 7.4) was mixed with0.1 ml of a borate saline buffer, pH 7.4, (control) or a sample solutionin the same buffer, and 0.1 ml of a thrombin solution (5 units/mn)supplied by Mochida Pharmaceutical Co., Ltd. was added to the solutionsin an ice bath. Immediately after mixing, the reaction mixture wastransferred from the ice bath to a bath maintained at 25° C. Coagulationtimes were taken as the period between the time of transference to the25° C. bath and the time of the first appearance of fibrin threads. Inthe cases where no drug samples were added, the coagulation time was50-55 seconds.

The experimental results are summarized in Table P. The term"concentration required to prolong the coagulation time by a factor oftwo" is the concentration of an active ingredient required to prolongthe normal coagulation time 50-55 seconds to 100-110 seconds.

The concentration required to prolong the coagulation time by a factorof two for the known antithrombotic agents. N²-(p-tolylsuofonyl)-L-arginine methyl ester, was 1100 μM.

The inhibitors are shown in Table I by indicating R and R' in thegeneral formula (II) and the added acid.

When a solution containing an N² -naphthalenesulfonyl-L-argininederivative of this invention was administered intravenously into animalbodies, the high antithrombotic activity in the circulating blood wasmaintained for from one to three hours. The halflife for decay of theantithrombotic compounds of this invention in circulating blood wasshown to be approximately 30 minutes; the physiological conditions ofthe host animals (rat, rabbit, dog and chimpanzee) were well maintained.The experimental decrease of fibrinogen in animals caused by infusion ofthrombin was satisfactorily controlled by simultaneous infusion of thecompounds of this invention.

The acute toxicity values (LD₅₀) determined 24 hours after oraladministration of substances of formula (I) in mice (male, 20 g) rangefrom about 1,000 to 10,000 milligrams per kilogram of body weight.

The therapeutic agents of this invention may be administered alone or incombination with pharmaceutically acceptable carriers, the proportion ofwhich is determined by the solubility and chemical nature of thecompound, chosen route of administration and standard pharmaceuticalpractice. For example, the compounds may be injected parenterally, thatis, intramuscularly, intravenously or subcutaneously. For parenteraladministration, the compounds may be used in the form of sterilesolutions containing other solutes, for examples, sufficient saline orglucose to make the solution isotonic. The compounds may be administeredorally in the form of tablets, capsules, or granules containing suitableexcipients such as starch, lactose, white sugar and the like. Thecompounds may be administered sublingually in the form of troches orlozenges in which each active ingredient is mixed with sugar or cornsyrups, flavoring agents and dyes, and then dehydrated sufficiently tomake the mixture suitable for pressing into solid form. The compoundsmay be administered orally in the form of solutions which may containcoloring and flavoring agents.

Physicians will determine the dosage of the present therapeutic agentswhich will be most suitable for humans, and dosages vary with the modeof administration and the particular compound chosen. In addition, thedosage will vary with the particular patient under treatment.

When the composition is administered orally, a larger quantity of theactive agent will be required to produce the same effect as caused witha smaller quantity given parenterally. The therapeutic dosage isgenerally 10-50 mg/kg of active ingredient parenterally, 10-500 mg/kgorally per day.

Having generally described the invention, a more complete understandingof the synthetic process for the compounds of this invention can beobtained by reference to the following specific examples, which areincluded for purposes of illustration only and are not intended to belimiting unless otherwise specified. The therapeutic agents of thisinvention are effective in mammals, including humans. A number of aminoacid t-butyl esters used as starting materials in the preparation of theherein claimed compounds have not previously been reported in thechemical literature. However, such compounds are easily prepared fromconventional procedures such as is taught by A. J. Speziale et al J.Organic Chemistry 25 731 (1960).

EXAMPLE 1

To a solution of 1.0 gram of L-arginine methyl ester dihydrochloride in50 ml of dichloromethane and 1.15 gram of triethylamine, was added 1.03gram of 6-dimethylamino-2-naphthalenesulfonylchloride with stirring atroom temperature. After being stirred for 5 hours at room temperature,the reaction mixture was poured into 30 ml of water.

After separation of the aqueous layer, the dichloromethane solution wasdried over anhydrous Na₂ SO₄, and filtered off, and then the solutionwas evaporated under reduced pressure to give N²-(6-dimethylamino-2-naphthalenesulfonyl)-L-arginine methyl ester. To thesolid was added ethyl ether saturated with dry hydrogen chloride, and N²-(6-dimethylamino-2-naphthalenesulfonyl)-L-arginine methyl esterdihydrochloride was obtained in 87% yield;

    ______________________________________                                        Elemental analysis (as C.sub.19 H.sub.29 O.sub.4 N.sub.5 S . 2HCl)                      C        H          N                                               ______________________________________                                        Calculated: 46.15      5.91       14.17                                       Found:      46.08      5.89       14.09                                       ______________________________________                                    

EXAMPLE 2

A 3.3 gram amount of 4-ethyl-[N^(G) -nitro-N²-(6-dimethylamino-2-naphthalenesulfonyl)-L-arginyl]piperidine wasdissolved in 50 ml of ethanol and 5 ml of acetic acid. A 0.5 gram amountof palladium-black was added and the mixture was shaken in a stream ofhydrogen for 100 hours at room temperature. After filtering off thecatalyst, the filtrate was evaporated to give a viscous oily product.Reprecipitation from methanolethyl ether gave 4-ethyl-[N²-(6-dimethylamino-2-naphthalenesulfonyl)-L-arginyl]piperidine acetate ina powder form in 75% yield.

    ______________________________________                                        Elemental analysis (as C.sub.25 H.sub.38 O.sub.3 N.sub.6 S . 2CH.sub.3        COOH)                                                                                   C        H          N                                               ______________________________________                                        Calculated: 55.93      7.45       13.50                                       Found:      55.59      7.28       13.82                                       ______________________________________                                    

EXAMPLE 3

To a mixture of 1.0 gram of 4-ethyl-1-(L-arginyl)-piperidine and 0.61gram of K₂ CO₃ in 10 ml of water was added dropwise a solution of 1.3gram of 5-diethylamino-1-naphthalenesulfonyl chloride in 30 ml ofdioxane with vigorous stirring for a period of over 30 minutes whilemaintaining the temperature at 0° C. The reaction mixture was stirredfor additional 5 hours and the formed precipitate was removed byfiltration. The solvent was evaporated, and to the residue was added 50ml of CHCl₃. A small amount of the undissolved material was filtered andthe solution was dried over anhydrous Na₂ So₄. To the stirred solutionwas added 20 ml of ether containing 1.0 gram of acetic acid toprecipitate 4-ethyl-1-[N²-(5-diethyl-1-naphthalenesulfonyl)-L-arginyl]piperidine diacetate, whichwas purified by reprecipitation from a methanol-ethyl ether mixture in76% yield.

    ______________________________________                                        Elemental analysis (as C.sub.28 H.sub.42 O.sub.3 N.sub.6 S . 2CH.sub.3        COOH)                                                                                   C        H          N                                               ______________________________________                                        Calculated: 57.21      7.74       12.91                                       Found:      57.02      7.65       12.66                                       ______________________________________                                    

EXAMPLE 4

A 1.2 gram amount of 4-acetyl-1-[N^(G) -nitro-N²-(6-dimethylamino-2-naphthalenesulfonul)-L-arginyl]piperidine wasdissolved in a mixture of 0.44 grams of anisole and 10 ml of hydrogenfluoride, and the mixture was stirred for 30 minutes in an ice-bath. Thehydrogen fluoride was evaporated in vacuo to afford an oily product,which was washed well with 100 ml of dry ethyl ether to remove thehydrogen fluoride. Reprecipitation from methanol-ethyl ether gave4-acetyl-1-[N²-(6-dimethylamino-2-naphthalenesulfonyl)-L-arginyl]piperidinedihydrofluoride in a powder form in 80% yield.

    ______________________________________                                        Elemental analysis (as C.sub.25 H.sub.36 O.sub.4 N.sub.6 S . 2HF)                       C        H          N                                               ______________________________________                                        Calculated: 53.94      6.88       15.10                                       Found:      53.73      6.70       15.00                                       ______________________________________                                    

    __________________________________________________________________________     ##STR15##                       Addition                                                                             (Ex.cesspro-tionara-Prep-                                                         or m.p.ertyProp-                                                                  Lower:FoundUpper:                                                            CalculatedElemental                                                           Analysis   twofactor                                                                    oftime by                                                                     acoagulationprolo                                                             ng therequired                                                                torationConcen-      No.                                                                              R           R'               Moiety No.)                                                                              (°C.)                                                                      C  H   N  (μM)              __________________________________________________________________________        ##STR16##                                                                                 ##STR17##       2CH.sub.3 COOH                                                                       2   powder                                                                            55.93 55.59                                                                      7.45 7.28                                                                         13.50 13.82                                                                      0.3                  2                                                                                 ##STR18##                                                                                 ##STR19##       2HF    4   "   53.94 53.73                                                                      6.88 6.70                                                                         15.10 15.00             3                                                                                 ##STR20##  "                2CH.sub.3 COOH                                                                       2   "   55.93 55.68                                                                      7.45 7.29                                                                         13.50 13.41             4                                                                                 ##STR21##  "                "      2       53.83 53.53                                                                      7.10 7.00                                                                         13.45 13.25             5  OCH.sub.3   "                2HCl   1   "   46.15                                                                            5.91                                                                              14.17                                                              46.08                                                                             5.89                                                                             14.09                       6                                                                                 ##STR22##                                                                                 ##STR23##       2CH.sub.3 COOH                                                                       3   "   57.21 57.02                                                                      7.74 7.65                                                                         12.91 12.16                                                                      0.3                  __________________________________________________________________________

what is claimed as new and intended to be covered by Letters Patent ofthe U.S. is:
 1. N² -naphthalenesulfonyl-L-arginine amides having theformula ##STR24## or the acid addition salts threof with apharmaceutically acceptable acid wherein R₁ is alkenyl of not more than10 carbon atoms, or substituted alkyl containing not more than 20 carbonatoms wherein said substituent is a member selected from the classconsisting of alkoxy, alkoxycarbonyl, arylcarbamoyl acyl, acyloxy,N,N-polymethylenecarbamoyl and carboxy, and R₂ is aryl, cycloalkyl,aralkyl or cycloalkylalkyl, respectively containing not more than 15carbon atoms and R' is 1-naphthyl substituted with a member selectedfrom the class consisting of 2-dialkylamino, 3-dialkylamino,4-dialkylamino, 6-dialkylamino, 7-dialkylamino, 8-dialkylamino,respectively containing not more than 20 carbon atoms, and5-dialkylamino containing 3-20 carbon atoms; or 2-naphthyl substitutedwith dialkylamino containing not more than 20 carbon atoms.
 2. A methodof inhibiting activity and suppressing activation of thrombin in vivowhich comprises administering to a mammal a pharmaceutically effectiveamount of a compound of claim 1.